Prosthetic ankles and feet are known. For example, U.S. Pat. No. 5,030,239 discloses a biomechanical ankle which imitates the three primary categories of movement in a human foot. Parallel sole and limb supporting plates are held in spaced relationship by an upright post. The limb supporting plate is connected to the post with a ball and socket joint. A helical spring is fixed between the plates to provide resilient support to the anterior portion of the foot in imitation of normal muscular control. The ball and socket joint, in cooperation with the spring, permits the biomechanical ankle to imitate the inversion-eversion, plantar flexion-dorsiflexion, and lateral rotation found in a normal human foot.
U.S. Pat. No. 7,108,723 B2 discloses a prosthesis for improving the gait and comfort qualities of the amputee that participates in walking, running and jumping activities. A foot and an ankle of the prosthesis are monolithically formed as a resilient member including a strut which forms an ankle joint. A hole extends through the resilient member with the periphery of the hole forming an anterior side surface of the strut. The resilient member anterior to the hole includes a gap to permit motion about the ankle joint axis while providing a stop in dorsiflexion. The hole is elongated upwardly such that the strut is upstanding and anterior convexly curved.
However, there remains a need for a modular prosthetic foot, in particular, a modular prosthetic foot that mimics the subtalar joint of a human foot.